Re: [parisc-linux] interesting linker behaviour :)

[Randolph Chung <randolph@tausq.org>]

> Good catch!  I've hit this problem before but under HP-UX.  GAS doesn't
> support the alternate entry point fixup needed to support multiple
> entry points to a function.  I don't think anyone has tried to support
> this with the ELF tools.  There could be some nasty interactions with
> the HP unwind data when you start adding multiple entry points to a
> function.

yeah, it will break unwinding :(

> I haven't looked at this in detail but possibly you can change the
> fixup table to contain pc-relative offsets.  I looked at this
> when I reworked the casesi pattern in GCC a few months ago.  This
> makes the table smaller and in many cases the number of instructions
> is less than that with branches in the table (particularly for the
> PIC case).  

well, this is what we used to do, but we don't do this now because it
requires us to be able to do a pc-relative calculation between code in
two different sections (text and fixup), and GAS doesn't allow that
either.

for now i'm using the solution we are using for 64-bit code, which is to
use a manually created long-branch stub (ldil/ldo/bv). since this is 
anyway in a slow-path the performance hit is probably negligible.

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/
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